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Fix Race conditions #359

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Fix Race conditions #359

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38 changes: 31 additions & 7 deletions SDWebImageSwiftUI/Classes/ImageManager.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -61,9 +61,27 @@ public final class ImageManager : ObservableObject {

var currentURL: URL?
var transaction = Transaction()
var successBlock: ((PlatformImage, Data?, SDImageCacheType) -> Void)?
var failureBlock: ((Error) -> Void)?
var progressBlock: ((Int, Int) -> Void)?

// Thread-safe callback properties
private let callbackQueue = DispatchQueue(label: "ImageManager.callbacks", qos: .userInitiated)
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@dreampiggy dreampiggy Sep 3, 2025 •
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The ImageManager is not a shared instance. I remember it's just behaved as ObservedObject used for View (it like a ViewModel), so it's created everytime new URL is provided.

Does this (means, you create each DispatchQueue in each Manager instance) cause queue explosion ?

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Valid point!
How do you propose I fix it?

private var _successBlock: ((PlatformImage, Data?, SDImageCacheType) -> Void)?
private var _failureBlock: ((Error) -> Void)?
private var _progressBlock: ((Int, Int) -> Void)?

var successBlock: ((PlatformImage, Data?, SDImageCacheType) -> Void)? {
get { callbackQueue.sync { _successBlock } }
set { callbackQueue.sync { _successBlock = newValue } }
}

var failureBlock: ((Error) -> Void)? {
get { callbackQueue.sync { _failureBlock } }
set { callbackQueue.sync { _failureBlock = newValue } }
}

var progressBlock: ((Int, Int) -> Void)? {
get { callbackQueue.sync { _progressBlock } }
set { callbackQueue.sync { _progressBlock = newValue } }
}

public init() {}

Expand Down Expand Up @@ -96,9 +114,11 @@ public final class ImageManager : ObservableObject {
progress = 0
}
self.indicatorStatus.progress = progress
if let progressBlock = self.progressBlock {
// Capture progress callback in thread-safe way
let progressCallback = self.progressBlock
if let progressCallback = progressCallback {
DispatchQueue.main.async {
progressBlock(receivedSize, expectedSize)
progressCallback(receivedSize, expectedSize)
}
}
}) { [weak self] (image, data, error, cacheType, finished, _) in
Expand All @@ -112,6 +132,10 @@ public final class ImageManager : ObservableObject {
// So previous View struct call `onDisappear` and cancel the currentOperation
return
}
// Capture completion callbacks in thread-safe way
let successCallback = self.successBlock
let failureCallback = self.failureBlock

withTransaction(self.transaction) {
self.image = image
self.error = error
Expand All @@ -122,9 +146,9 @@ public final class ImageManager : ObservableObject {
self.indicatorStatus.isLoading = false
self.indicatorStatus.progress = 1
if let image = image {
self.successBlock?(image, data, cacheType)
successCallback?(image, data, cacheType)
} else {
self.failureBlock?(error ?? NSError())
failureCallback?(error ?? NSError())
}
}
}
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